A variety of different products are shipped in cargo containers. Products are packed into the container by a shipper, and then the container doors are closed and secured with some type of lock. The container is then transported to a destination, where a recipient removes the lock and unloads the container.
The shipper often finds it advantageous to have some form of monitoring while the container is being transported. For example, the cargo within the container may be relatively valuable products such as computers or other electronic devices, and thieves may attempt to break into the container and steal these products if the container is left unattended during transport. Alternatively, the cargo may be products such as fresh fruit, for which it is advantageous to continuously monitor environmental conditions such as temperature and humidity, in order to avoid or minimize spoilage. As still another example, the cargo may include items that can be damaged by moisture that leaks into the container during a rainstorm, or that escapes from some other item in the container.
It is not cost-feasible to have a person watch a container at all times in order to provide security and/or monitoring. Accordingly, electronic systems have previously been developed to provide a degree of automated security and/or monitoring. Although these pre-existing systems have been generally adequate for their intended purposes, they have not been satisfactory in all respects.